Heatmap display of correlations between HRneg breast cancer expression of eight different gene signatures. Each square within a pyramid displays the Pearson correlation coefficient (Rp) between a pair of signatures as indicated on the horizontal and vertical axes. *Significant correlations (P < 0.05). Correlations computed from training cohort (n = 199) are displayed on the left, and correlations computed from validation cohort (n = 75) are displayed on the right. Red-blue color scale is used to reflect the magnitude of Rp, with red denoting consistent positive and blue denoting consistent negative Rp values across each cohort. Squares are colored grey (without Rp values) for inconsistent associations (opposite Rp directions) between cohorts. CSR, core serum response; HRneg, hormone receptor-negative; GGI, genomic grade index; IFN, interferon; IR-7, immune response signature with 7-gene immune response module; MS-14, Celera 14-gene metastasis score; NKI-70, 70-gene Mammaprint signature; ONCO-RS, Oncotype/Genomic Health recurrence score; Rp, Pearson correlation coefficient; STAT1, signal transducer and activator of transcription 1; Tneg, triple-negative.